For purposes of thermal insulation, metallurgical furnaces are provided with an interchangeable, metallic inner lining, on which insulating materials made of a fireproof material, such as fireproof clay, can be attached. The prevailing temperatures inside the furnace are so high, that the lining must be cooled. Cooling plates having integrated coolant channels are used in this connection. Such cooling plates are usually situated between the furnace shell and the furnace brick lining, and connected to the cooling system of the furnace. As a rule, the sides of the cooling plates facing the interior of the furnace are provided with fireproof material.
Cooling plates are known, in which the coolant channels are formed by cast-iron pipes. These cooling plates do not effectively dissipate heat. In part this is because of the low thermal conductivity of cast iron. Additionally, effective heat dissipation may be prevented by the resistance between the cooling pipes and the plate member caused by an oxide layer or an air gap.
Copper and copper alloys have a considerably better thermal conductivity than cast iron. In this context, DE 29 07 511 C2 describes a cooling plate for shaft furnaces, which is made of copper or a low-alloyed copper alloy, and is manufactured from a forged or rolled copper block. In this type of construction, coolant channels produced by mechanical deep-hole drilling are situated in the interior of the cooling plate. The coolant channels introduced into the cooling plate are sealed by soldering in or welding in screw caps. Inlet boreholes, which lead to the coolant channels, and are welded. or soldered to connecting pieces necessary for coolant supply or removal, are situated on the back of the cooling plate.
In addition, the related art of DE 198 01 425 A1 provides for the introduction of coolant channels into a cooling plate by mechanically removing material, and provides for covering the resulting channel pattern with a covering plate. To this end, the covering plate must be attached to the cooling plate, so as to form a seal. However, this procedure is particularly disadvantageous because of the necessary welding steps.
Coolant channels that are not round, e.g., channels that have oval or oblong cross-sections, have proven themselves reliable, because they provide a larger surface for transferring heat. Cast cooling plates, which are made of a copper material and have non-circular cooling channels, are known in this context. However, these have the disadvantage of the material being coarse-grained and non-uniform. This results in a poor thermal conductivity and the danger of early material fatigue. Furthermore, it is disadvantageous that structural defects of the material or damage to the material, such as microcracks on the cast cooling plate, are difficult to detect.